Method for the production of high-temperature gases

ABSTRACT

Hot gases are formed by establishing an electrical discharge in substantially uniform distribution throughout a zone, passing a gas through said zone in the absence of a flame and in contact with said discharge to increase the temperature of said gas, said electrical discharge being distributed substantially uniformly through said gas. High-temperature gases formed by said method are useful in the production of carbon black.

Zia/121 United States Paten Gunnell et a1. g

il-IIWII nuunl [451 Jan. 18,1972

[54] METHOD FOR THE PRODUCTION OF HIGH-TEMPERATURE GASES [72] Inventors:Thomas J. Gunnell; Albert F. Stegelman,

= both of Bartlesville, Okla.

[73] Aaslgnee: Phillips Petroleum Company [22] Filed: Jan. 30, 1969 21Appl. No.: 795,323

' Related U.S. Application Data [63] Continuation of Ser. No. 518,332,Jan. 3, 1966, abandoned.

[52] US. Cl ..219/121 P, 13/1, 23/2093 [51] Int. CL. 105b 7/00 [58]Field of Search ..23/209.3, 259.5; 204/173, 164, 204/172, 323, 324;13/149; 2l9/l0.4l, 10.65, 121 P [56] Relerences Cited UNITED STATES PATENTS 3,004,137 10/196 g g nz....,., ...2o4/64x 3,051,639 8/1962Anderson ..204/172 3,232,746 2/1966 Karlovitz.... ..23/209.3 X 3,288,6961 l/l 966 Orbach ..204/173 3,344,051 9/ l 967 Latham ...204/ l 733,409,403 1 H1968 Bjomson et al 23/2093 Primary Examiner-Edward J. MerosAttorney--Young and Quigg [57] ABSTRACT Hot gases are formed byestablishing an electrical discharge in substantially'uniformdistribution throughout a zone, passing a gas through said zone in theabsence of a flame and in contact with said discharge to increase thetemperature of said gas, said electrical discharge being distributedsubstantially uniformly through said gas. High-temperature gases formedby said method are useful in the production of carbon black.

9215 8 5 1""? guns PATENTED JANI 3 1912 SHEET 1 [IF 2 a F F INVENTOR.

T. J. GUN NELL BY A. F. STEGELMAN A T TORNE VS PATENTED JAM 8 I972 SHEET2 [IF 2 INVENTOR.

T. J. GUN NELL BY A. F. STEGELMAN fifi ATTORNEYS METHOD FOR THEPRODUCTION OF HIGH- TEMPERATURE GASES This is a continuation-in-part ofour application Ser. No. 518,332, filed Jam 3,. 1966 which issued asU.S. Pat. No. 3,468,632.

This invention relates to a method and apparatus for production of hightemperature gases and carbon black. In one aspect this invention relatesto apparatus for production ofhigh temperature gases useful in theproduction of carbon black, and elsewhere. In another aspect thisinvention relates to a method for the production of high-temperaturegases. In another aspect this invention relates to a method for theproduction of carbon black.

For several years carbon black has been produced in large quantities infurnaces. For example, it is known in the prior art to produce carbonblack by directing a hot oxidizing or combustion gas in a generallyhelical path adjacent the periphery of a generally cylindrical reactionzone and directing a carbonaceous reactant material axially into saidzone inside the helically moving mass of hot gas. The reactant isthereby rapidly heated to a carbon black-forming temperature and reactedin said zone to form carbon black, which is subsequently recovered.Processes of this type are illustrated in U.S. Pat. Nos. 2,375,795;2,375,796; 2,375,797; and 2,375,798 (1945 Another similar process,disclosed and claimed in US. Pat. No. 2,564,700 (1951), involves theinjection of a combustible mixture of fuel and oxidizing gascircumferentially or tangentially into a combustion zone and thereaction of the mixture by combustion near the periphery of said zone.The resulting combustion gas, at a high temperature, travels in agenerally spiral path towards the axis of said combustion zone and isthen directed in a generally helical path adjacent the periphery of areaction zone which is contiguous with, of smaller diameter than, and inopen communication with, said combustion zone. A carbonaceous reactantis directed along the common axis of said zones and is rapidly heated toa carbon black-forming temperature by virtue of heat directly impartedfrom the helically-moving combustion gas. The reactant is reacted withinthe reaction zone to form carbon black, which is subsequently recovered.This type of process is known as a preeombustion process, since the hotgas is substantially completely formed by combustion prior to contactwith the reactant.

The reaction mixture formed in processes of the type described abovecomprises a suspension of carbon black in combustion gas. It is known inthe prior art to withdraw such a mixture from the reaction zone and tocool the mixture suddenly by the direct injection thereinto of a coolingliquid, such as water, in order to cool the mixture suddenly to atemperature at which no further reaction can occur.

In the above-described processes for producing carbon black, largequantifies of heat are required. In those areas where fuel supplies arelimited or must be imported, the cost of the fuel necessary to supplythe required amount of heat can be excessive. It would thus be desirableto supply a portion of the heat from other sources. In some areas heatfrom electrical power is more readily available or less expensive thanheat obtained from the burning of a fuel or the carbonaceous reactant.However, it is not desirable or feasible in the production of carbonblack to supply all the necessary heat by electrical power because,generally speaking, carbon blacks produced in an atmosphere ofcombustion gases give superior results for most uses.

Methods for increasing the temperature of a flame and the combustiongases resulting therefrom by superimposing an electrical dischargeacross the flame are known. However, the methods and apparatus of theprior art are not adapted for the production of carbon black becausethey require the use of cooled electrodes whichresult in large heatlosses. Large heat losses are definitely undesirable in a carbon blackreaction system. Furthermore, the methods and apparatus of the prior artfor the production of carbon black are'not adapted for supplying a partof the necessary heat from sources other than combustion of the fueland/or a portion of the make hydrocarbon (carbonaceous reactant). Thepresent invention overcomes these deficiencies of both fields of theprior art.

The present invention provides a method and an apparatus for theproduction of carbon black wherein only a portion of the necessary heatis supplied by combustion of a fuel and/or a portion of the makehydrocarbon and the remainder is supplied by electrical power. Thus, inthe production of carbon black in accordance with the present invention,a portion of the necessary heat is obtained from that contained in amass of hot combustion gases and the remainder is supplied bysuperimposing a distributed discharge on said gases, thus electricallyaugmenting the heat in said combustion gases. The present invention alsoprovides an improved apparatus and an improved method for the productionof high-temperature gases.

An object of this invention is to provide a method and an apparatus forthe production of valuable carbon blacks. Another object of thisinvention is to provide an improved apparatus for the production ofhigh-temperature gases which are useful in the production of carbonblack, and elsewhere. Another object of this invention is to provide animproved apparatus for the production of high-temperature gases byelectrical augmentation of a flame and/or the resulting combustion gaseswherein cooling of the electrodes is eliminated. Another object of thisinvention is to provide a method of producing carbon black wherein apart of the necessary heat is supplied from sensible heat normallycontained in a mass of hot combustion gases and the remainder issupplied from electrical power. Another object of this invention is toprovide a method of producing carbon black wherein the heat supplied bya flame and/or a mass of hot combustion gases is augmented bysuperimposing a distributed electrical discharge across and/or throughsaid flame and/or through said gases. Other aspects, objects, andadvantages of the invention will be apparent to those skilled in the artin view of this disclosure.

Thus, according to the invention, there is provided an apparatus forproducing a stream of high-temperature gases, comprising, incombination: a generally cylindrical heat and electrically insulatedfirst chamber; a first electrode means comprising" an electricallyconducting refractory liner disposed within said chamber around theinner wall thereof for at least a portion of its length; a secondelectrode means spaced apart from the upstream end of said liner; meansfor introducing a stream of gases into the space between saidelectrodes; and means for creating a substantial distributed electricaldischarge between said first and second electrode means.

Further according to the invention, there is provided a process forproducing a stream of high-temperature gases, which process comprises:establishing and maintaining a rotating mass of combustion gases in agenerally cylindrical first zone; establishing and maintaining asubstantial electrical discharge distributed across said rotating massof gases from a first locus to a second locus; and passing substantiallyall of said gases through said discharge to increase the temperature ofsaid gases.

Still further according to the invention, there is provided a processfor producing carbon black which, broadly speaking, comprisesmaintaining carbon black-producing conditions in a zone for producinghigh-temperature gases from hot combustion gases and fonning said carbonblack from an essentially hydrocarbon feedstock introduced into saidzone and/or from a portion of the fuel used in making said combustiongases.

FIG. 1 is a diagrammatic illustration, partly in cross section, of onetype of furnace which can be employed in the practice of the invention.

FIG. 2 is a cross section along the lines 2-2 of FIG. 1.

FIG. 3 is a diagrammatic illustration, partly in cross section,

of another type of furnace which can be employed in the practice of theinvention.

FIG. 4 is a view, partly in cross section, illustrating details of theupstream electrode assembly shown as being employed in the furnace ofFIG. 1, but which can also be employed in the furnace of FIG. 3.

FIG. 5 is a view, partly in cross section, of another upstream electrodeassembly which can be employed in the furnace of either FIG. 1 or FIG.3.

Referring now to the drawings, wherein like reference numerals areemployed to denote like elements, the invention will be more fullyexplained. In FIG. 1 the furnace there illustrated, designated generallyby the reference numeral 10, comprises a generally cylindrical heat andelectrically insulated chamber 12 having a length greater than itsdiameter. As shown in the drawing, said chamber 12 is formed from a heatand electrical insulating material 14. Any suitable heat and electricalinsulating material, e.g., aluminum oxide, silica,

magnesia, silica-magnesia, silica -zirconia, and the like, can beemployed in the practice of the invention. A first electrode meanscomprising an electrically conducting refractory liner 16 is disposedwithin said chamber 12 around and along the inner wall thereof.Preferably, the upstream end of said liner is spaced apart from theupstream end of said chamber 12, leavingaportion of said inner wallelectrically nonconducting. Said liner 16 can be fabricated from anysuitable electrically conducting refractory, e.g., silicon carbide,zirconia, thoria, titania etc. If desired, the upstream end portion ofsaid liner 16 can be fabricated in removable cylindrical sections asshown to facilitate the spacing of the upstream end of the liner fromthe upstream end of chamber 12. Thus, a series of sections 13 and 13' ofthe same or different lengths, made of either a conducting refractory ornonconducting refractory material, can be employed. Said sections can beinserted or removed by parting the furnace at the flange 17. Varyingsaid spacing by means of said sections 13 and 13' provides one means forvarying the spacing between electrodes as discussed further hereinafter.An electrical conducting means comprising a bed of graphite powder 18having a graphite rod 20 embedded therein and a suitable electricalconnection 22 attached to said graphite rod extends through the metalshell and the insulating wall 14 of said chamber 12 into contact withsaid refractory liner 16. Said electrical conducting means thus providesmeans for furnishing an electrical connection to said liner 16 and,along with the electrical connection to an upstream electrode and 2power source, comprises means for establishing an electrical dischargebetween said electrodes. Any other suitable electrical power connectionto said liner l6 insulating material 36, e.g., magnesium silicate,magnesia, and

can be employed. As shown in the drawing, said bed of graphite powder 18is insulated from metal shell 15 by means of a suitable high temperatureinsulator 24, e.g., magnesium silicate, magnesia, and the like, whichextends a short distance into the heat and electrical insulation 14.

Another generally cylindrical chamber 26, having a diameter greater thanits length and greater than the diameter of said chamber 12 is connectedat its downstream end to the upstream end of said chamber 12 in axialalignment and open communication therewith. As shown in the drawing,said chamber 26 is also formed from a heat and electrical insulatingmaterial 14. At least one inlet tunnel 28 communicates tangentially withsaid chamber 26. Preferably, two of said inlet tunnels 28 and 28' areemployed as illustrated in FIG. 2. Although not shown in the drawing, itwill be understood that a transfer conduit connects with the downstreamend of chamber 12 atflange 35. Said transfer conduit can be the same as,smaller than, or larger in diameter than chamber 12. Quench inletconduits (not shown) are usually provided to the interior of saidtransfer conduit for quenching the effluent from chamber 12 when thefurnace is employed for production of carbon black. Said quenching iscarried out in conventional manner and reduces the temperature of theeffluentto a temperature below that at which carbon black is formed,e.g., to a temperature less than about l,500 F.

An electrode chamber 30 adjoins the upstream end of said chamber 26 inaxial alignment and open communication therewith. As shown in thedrawing, said electrode chamber 30 is formed from or in a refractorymaterial 14 as are said chambers 12 and 26. An insulator plug,designated generally by thereference numeral 32, comprises a metal shell34 havthe like disposed within said metal shell 34. Said threads provideanother means for varying the spacing between the upstream electrode 46and the downstream electrode 16. A passageway 38 extends through saidbody of insulating material 36 into a communication with electrodechamber 30 for supplying a purge gas thereto, if desired. The use of apurge gas is not essential in the practice of the invention. When apurge gas is desired to prevent recirculation in the electrode chamber30, any suitable gas such as air, nitrogen, flue gases, helium, argon,and the like, can be used.

An upstream electrode assembly extends through said body of insulatingmaterial and into said electrode chamber 30. As shown more clearly inFIG. 4, said electrode assembly comprises a first conduit 40 having aninner end and an outer end with respect to said electrode chamber 30. Asecond conduit 12, also having an inner end and an outer end withrespect to said electrode chamber 30, is disposed 'within said firstconduit 40 to provide an annular space 44 therebetween. Said outer endof said second conduit 42 extends beyond said outer end of said firstconduit 40. A cap 46, formed of a metal having a high thermalconductivity, e.g., copper, silver, gold, platinum, tungsten, etc., ispositioned on and surrounds the inner end of said first conduit 40 andthe inner end of said second conduit 42 leaving a space between saidconduit ends and the inner end wall of said cap. An aperture 48 isprovided in said cap 46. Athird conduit 50, also having an inner end andan outer end with respect to said electrode chamber 30, is positionedwithin said second conduit 42 to provide an annular space 52therebetween. It will be noted that the inner end of said third conduit50 extends through said aperture 48 in cap 46. The outer end of saidthird conduit 50 extends beyond the outer end of said second conduit 42.As shown in the drawing, the outer end of first conduit 40 is joined tothe outer end portion of said second conduit 42 by means of a suitableclosure means, thus closing the outer end of annular space 44. The outerend of second conduit 42 is attached to the outer end portion of thirdconduit 50 by means of a suitable closure means, thus closing saidannular space 52. Inlet 54 and outlet 56 provide means for circulating asuitable cooling medium, e.g., water or other suitable fluid, throughannular space 52, the space 58 withincap 46, and annular space 44, thusproviding means for cooling the entire electrode assembly.

In said electrode assembly the face of cap 46 is the working portion ofthe electrode. However, since the conduits connected to said cap conductthe current thereto, they are a part of the electrode. Also, it will beunderstood that when an electrical connection is made to conduit 50 (asdescribed elsewhere herein) that the fluid conduits connected to 54 and56 are nonconducting.

Any suitable electric circuit connected to a suitable power source,either AC or DC, can be employed in the practice of the invention. Thecircuit illustrated diagrammatically in FIG. 1 comprises a lead 19,which may be grounded, connected via the means shown at 22, 20, and 18mthe liner electrode 16, and another lead 21 connected to the upstreamelectrode 46 via a suitable connection to conduit 50. An input circuit23 including a transformer 25 is connected to supply alternating currentto said lead wires 19 and 21. As a safety measure, to prevent arcing andrunaway current in case the voltage should become too high, a resistance27 and an inductance 29 can be provided in said input circuit 23. Saidcircuit and connecting lead wires, per se, form nopart of the inventionand any other suitable means for supplying power to said electrodes 16and 46 can be employed. I

In FIG. 3 there is shown another furnace in accordance with theinvention, the downstream portion of which is like the nace of FIG. 3differs from the furnace of FIG. 1 primarily in the omission of chamber26. In the furnace of FIG. 3, the electrode chamber 30 adjoins theupstream end of said chamber 12 in axial alignment and opencommunication therewith. As shown in the drawing, the upstream electrodeassembly comprises an insulator plug, designated generally by thereference numeral 32', which is substantially the same as said insulatorplug described above in connection with FIGS. 1 and 4. Although notshown, a purge gas passageway 38 can be provided in insulator plug 32'.Extending through said insulator plug 32' and into said electrodechamber 30 is a solid electrode 60. As here shown, said electrode isformed from a suitable refractory material, e.g., silicon carbide,thoria, zirconia, etc. If desired, the insulator plug and electrodeassembly of FIG. 1 can be employed in the furnace of FIG. 2. Auxiliaryinlet 33 communicating with chamber 30 is provided for introduction ofpurge gas, discharge initiator, or other material. In FIG. 5 there isshown another form of a fluid-cooled electrode assembly which can beemployed in the practice of the invention. This electrode assemblycomprises an outer conduit 62 having an inner conduit 64 disposedconcentrically therein. A metal cap 66 formed of a suitable metal havinga high thermal conductivity (similar to cap 46 of FIG. 4) is attached toand surrounds the inner end of first conduit 62 and second conduit 64,closing the inner ends of said conduits and the annular space betweensaid conduits 62 and 64, similarly as in FIG. 4, and thus providing forcirculation of a cooling medium, e.g., water, through conduit 64,annular space 63, and through outlet 65.

Referring again to FIGS. 1 and 2, in the operation of one embodiment ofthe invention a combustible mixture of a fuel and a freeoxygen-containing gas, e.g., air, is introduced into at least one oftangential tunnels 28 and 28' which communicate tangentially withchamber 26. The fuel used in forming said combustible mixture can be anysuitable fuel, either liquid, solid, or gaseous. Generally speaking, agaseous fuel such as natural gas or a normally gaseous hydrocarbon ispreferred. Liquid hydrocarbon fuels are the next most preferred fuel.Any suitable means can be employed for introducing and/or forming saidcombustible mixture in inlet tunnels 28 and 28', e.g., the conduitsshown in FIG. 2, and the burner shown in U.S. Pat. No. 2,780,529.Burning of said combustible mixture is initiated and substantiallycompleted in inlet tunnel 28 and/or 28'. Any portion of said mixturewhich is not burned in said inlet tunnels is burned along the peripheryof chamber 26. Upon continued injection of combustible mixture into saidinlet tunnel 28 and/or 28', the resulting combustion mixture exitingtherefrom enters chamber 26 and follows a spiral path around same towardthe axis thereof. When the spiral becomes less than the diameter ofchamber l2, the gaseous flow changes from a spiral to a helical form,and following this latter pattern enters said chamber 12.

A distributed electrical discharge is initiated across and/or throughsaid combustion mixture in chamber 26. I Said discharge extends betweenupstream electrode 46 and downstream liner electrode 16. Forconvenience, electrode 46 is sometimes referred to herein as a firstlocus and electrode I6 as a second locus. When using AC current thedischarge can originate at either electrode. When using DC current theoriginating electrode will depend upon the polarity. Said discharge canbeinitiated in any of several ways. One way to initiate said dischargeis to increase the applied voltage. Another way is to supply anionization additive such as potassium chloride or nitrous oxide intosaid combustion mixture. Said ionization additive can be introduced inany suitable manner such as with the'fre'e oxygen-containing gas, or canbe introduced directly into chamber 26 by any suitable means.

For example, if only one of said tangential inlet tunnels is pie, ifchamber 26 is operating under oxygenrich conditions, then theintroduction of a fuel (preferably one with a high flame speed such asacetylene) through conduit 50 results in a higher temperature at theelectrode face and permits initiation of the discharge at a lowerapplied voltage. Fuels which can be used for this purpose are thosewhich decompose exothermically, i.e., liberate energy on decomposition.Included among such fuels are hydrogen, acetylene, ethylene, carbondisulfide, and metal hydrides such as antimony hydride, arsenic hydride,and the like. Gaseous fuels or fuels which can be readily vaporized arepreferred. Presently more preferred fuels are hydrogen, acetylene, andethylene. Similarly, when chamber 26 is operating under fuel-richconditions, then the introduction of a gas rich in oxygen throughconduit 50 results in a higher temperature at the electrode face. Thelocalized region of higher temperature at the electrode face results ina higher ionization and thus permits initiation of a smooth discharge ata lower applied voltage.

After the electrical discharge has been established, the voltage level(if a high voltage level was employed) can be decreased to the desiredoperating level, the stoichiometric ratio of the air and fuel mixtureand the throughput thereof adjusted to the desired levels, and thefurnace operated for the production of a stream of high temperaturegases as illustrated and discussed in the examples given hereinafter.

When it is desired to operate the furnace for the production of carbonblack, it is necessary to establish carbon blackproducing conditions inchambers 26 and 12. Said conditions include a temperature sufficient tocause the decomposition of at least a portion of the carbonaceousreactant into carbon black and an overall stoichiometric level ofpreferably not more than about 50 per cent and preferably above 25 percent. However, said levels can be affected to some extent by furnacegeometry and it is within the scope of the invention to employstoichiometric levels outside the above range so long as carbonblack-producing conditions are maintained. The temperature in chambers26 and 12 will preferably be above at least about 2,500 F.

Said overall stoichiometric level can be maintained at the desired levelin any suitable manner. Commonly, the stoichiometric level can becontrolled by controlling the amount of carbonaceous reactant orfeedstock introduced. Said stoichiometric level can also be controlledby controlling the level on the fuel-air mixture being burned intangential tunnels 28 and/or 28'. Or, a combination of said two methodscan be used.

Thus, when it is desired to operate the furnace for production of carbonblack, and usually after discharge has been established, a stream of areactant capable of being converted to carbon black, e.g., anessentially hydrocarbon material, is

then passed through said conduit 50 into chamber 26 and then intochamber 12. The electrical discharge augments the sensible heatcontained in the combustion gases, thus making it possible to supplyless heat from the combustion of the fuel for a given heat levelrequired for a given amount of reactant. If desired, said reactant canbe preheated by conventional means (not shown) prior to introduction viaconduit 50. Said reactant is passed axially through chamber 26 andenters chamber 12 while surrounded by the heated combustion gases.Carbon black is formed by the decomposition of said reactant due to theheat imparted thereto from the surrounding gases, and/or from partialburning of said reactant, under carbon black-producing conditions. Theresulting mixture of gases comprises a smoke containing -the carbonblack product in suspension and is withdrawn from chamber l2, quicklyquenched in a conventional manner to a temperature below that at whichcarbon black formation takes place, and is then passed to conventionalequipment for the separation of the carbon black therefrom.

In another embodiment of the invention, ahydrocarbonrich,,noncombustible mixture of a hydrocarbon and a freeoxygen-containing gas which will not burn at ordinary temperatures isintroduced via at least one of said tangential inlet tun- 7 nels 28 and28' into chamber 26. In this embodiment of the invention, the upstreamelectrode assembly shown in FIG. 3 can be conveniently employed ifdesired. When the swirling mass of gases has been established in chamber26, a distributed electrical discharge is established across and/orthrough said gases. Said discharge can be established by firstintroducing a stoichiometric mixture and then adjusting the mixture tothe hydrocarbon-rich condition after the dischargeis established. Othermethods as set forth in the examples can also be used to establish thedischarge. This electrical discharge quickly heats said gases to carbonblackproducing temperatures, thus providing carbon black-producingconditions, and at least a portion of the hydrocarbon in said mixture isconverted to carbon black in chamber 26 and chamber 12 and recovered asdescribed above. 1

In another embodiment of the invention, a mixture of combustion gasesresulting from the combustion of a combustible mixture of a fuel andfree oxygen-containing gas is introduced via the tangential inlet 59 inthe upstream end of chamber 12 in the furnace of FIG. 3. It will beunderstood that tangential inlet 59 communicates tangentially with theinner periphery of chamber 12, similarly as do inlet tunnels 28 and 28'with respect to chamber 26 in FIG. 1. Also, if desired, two inlets 59can be provided. In this embodiment of the invention, the up- 2 5 streamelectrode assembly shown in FIGS. 1 and 4 can be employed in the furnaceof FIG. 3. After the swirling mass of combustion gases has beenestablished in the upstream end of chamber 12, an electrical dischargeis initiated across and/or through said combustion gases to heat same asdescribed above. The remainder of the operation substantially followsthat described in the first above-described embodiment of the inventionwhere carbon black is produced.

In another embodiment of the invention, a mixture of a vaporous,essentially hydrocarbon reactant and a free oxygencontaining gas isintroduced via the tangential inlet 59 in chamber 12 of the furnace ofFIG. 3. In this embodiment of the invention, an upstream electrodeassembly substantially like that shown in FIG. 3 can be employed. Anelectrical discharge is established across and/or through said mixtureof hydrocarbon and free oxygen-containing gas and rapidly heats same tocarbon black-producing conditions and carbon black is produced andrecovered as described in the abovedescribed second embodiment of theinvention.

It will be noted that the electrical discharge employed inthe lowvoltage, high current discharge concentrated into a narrow filamentbetween two electrodes. In a plasma torch sufficient energy isintroduced in a concentrated discharge to ionize an inert gas, whereasin electrical augmentation as employed in this invention the distributeddischarge is throughout an already ionized conductive gas and is adiffuse discharge. The distributed discharge employed in the practice ofthis invention is a relatively high voltage, low current dischargewhich, because of its distribution, in effect supplies heating currentflowing through the mass of gases. At least two upon the degree ofionization of the turbulent mass of gases between the electrodes, thevolume of gases passing through the space between the electrodes, thedesign of the particular reactor or furnace employed, the amount of heatrequired, and other factors. Thus, the invention is not to be limited byany specific ranges of voltage or applied power, flow rates of gases, orstoichiometric ratios.

It will be noted that in the practice of the invention the discharge isdistributed across and/or through a rotating mass of gases. Said gasesare thus in a highly turbulent condition which greatly increases thediffuse conditions of the discharge. The highly turbulent conditions ofthe rotating combustion gases also contributes to establishment ofextremely uniform temperatures throughout the mass of gases. This is adistinct advantage over electrical augmentation processes wherein thedischarge is distributed across a flame because, as is well known,temperatures across a flame are not uniform.

The following examples will serve to further illustrate the invention.In these examples, a furnace having the general configuration of thatillustrated in FIGS. 1 and 2 was employed. Chamber 12 had an internaldiameter of about 2 inches and a length of about 14 inches. The lengthof the downstream electrode or liner 16 was about 12 inches. Thediameter .of chamber 26 was about 3.5 inches and the length thereof wasabout 1.5 inches. The diameter of electrode chamber 30 was about l.l2inches. These dimensions and all other dimensions given herein are givenfor illustrative purposes only and are not to be limiting upon theinvention. For convenience, due to availability, alternating current wasused in all the examples given below.

EXAMPLE I A series of runs was madefor the production ofhigh-temperature gases. The furnace employed was essentially the same asthat illustrated in FIGS. 1 and 2 except that said furnace was providedwith only one tangential inlet tunnel 28. The upstream electrode had aconfiguration like that illustrated in FIG. 5 and the diameter of thedownstream face of :said electrode was about seven-eighths inch. Thespacing between the face of said upstream electrode and the upstream endof liner electrode 16 was 3.5 inches. In these runs, mixtures of air andpropane at various stoichiometric levels (measured with respect to theair) were burned in said tangential tunnel and the resulting combustiongases passed tangentially into chamber 26. In Run No. 1 no discharge wasemployed. In

Run 2 a distributed discharge was established between said electrodesand across and/or through said gases by using potassium chloride as anionization initiator. Said potassium chloride was introduced into saidcombustion gases by subliming same into a stream of nitrogen and thenmixing said :nitrogen with the air stream. After Run 2 was completed,use of the ionization initiator was discontinued, and Runs 3 and 4 werecarried out successively by changing the operating conditions as shownin table I below. In Run 5 the discharge was initiated by temporarilyusing a stoichiometric air-propane mixture (for maximum flametemperature) and applying a high voltage (6,200 volts) to theelectrodes. After the discharge had been initiated, the stoichiometricratio on the air-propane mixture and the electrical power level wereadadvantages result from the application of such a discharge. justed tothe values indicated in table I below. Runs 6, 7, and 8 were anotherseries of successive runs carried out by initiating 'the discharge byusing potassium chloride, similarly as described above, and thenadjusting the operating conditions to the values indicated in table 1below. The refractory tern:

Q peratures for all runs were obtained by means of a thermocouplepositioned in therrnowell 31. Data for said runs are set forth in tableI I TABLE I Stolchio- Impe- Dischar e Retracmetric ance, Applied g topercent ohms volts Volts Amps K v a temp F 129 None 1, 775 129 2. 1 9757. 7 7. 7 129. 2. 2 300 1,560 6.3 9. 9 2,260 129 I 2.0 320 1,495 7.811.8 2,340 82 None l, 985 82 2.0 31 1,560 7 11.8 2,650 60 1. 9 1,560 7.211. 3 2,446 60 None l, 815

The data in the above table I show that the discharge voltage was lowerwhen the potassium chloride initiator was absent. The data also showthat relatively constant power levels could be obtained atstoichiometric levels ranging from 60 to 130 percent.

in other runs carried out in essentially the same manner, it

EXAMPLE II Another series of runs was carried out in the same apparatusas employed. n st n In fsss issgfii sspa izsfiss initiator was used. Thedischarge was initiated in Run No. l in the same manner as in Run 5 ofexample I. After the discharge had been initiated, the stoichiometriclevel and other conditions were adjusted to the desired values. Runs 2and 3 were each successive runs made upon completion of the previous runby adjusting the operating conditions to the new desired conditions. Thecomposition of the air-propane mixture was maintained at 80 per cent ofstoichiometric with an airflow of 520 s.c.f.h. after the discharge hadbeen initiated. Data from t series s m a t! .b.intsb1 2-.v; h

showed that constant power input could be obtained at differentcombinations of applied voltage and inductive impedance. However, thedata indicated that lower applied voltage and low inductive impedanceproduced a more favorable power factor.

EXAMPLE Ill Another series of runs was carried out employing the samefurnace and in substantially the same manner as in example 11 exceptthat all three runs were individual runs, ie. the discharge wasinitiated at the start of each run. No ionization initiator was used.These runs were carried out with a relatively constant applied voltageand inductive impedance to determine the effect of varying thestoichiometric level on electrical power input and discharge voltage.The data set forth in table III below show that power level and powerfactor were slightly higher at stoichiometric than at rich or leanconditions. Said data also indicate that the discharge voltage does notappear to vary appreciably under these conditions.

EXAMPLE IV Another series of runs was carried out in the same furnaceand in substantially the same manner as employed in example ii. In thisseries of runs the stoichiometric level of the airpropane mixture wasmaintained constant at 125 per cent and the air throughput was varied.Data from this set of runs are set forth in table IV below.

TABLE II lmpe- Discharge dance. Applied Power Run No ohms volts VoltsAmps Kw Kva. factor TABLE III Stolchiometric Impe- DischargeRefraclevel, dance, Applied Power tory Air rate, 3.0.1.11. percent ohmsvolts Volts Kw. factor temp., F.

TABLE IV Electric Discharge power Impepercent of Throughpu dance.Applied Power combustion Run No. s.c.i.h., air ohms volts Volts Kwfactor 1 power The inductive impedance was substantially constant forthe first five runs. As air throughput was increased, the dischargevoltage and powerinput increased slightly. The power factor wassubstantially constant. Run No. 6 was carried out at the same throughputas Run No. but with lower applied voltage and lower inductive impedance.These conditions produced an improvement inpower factor. The dischargeappeared to be more diffused at the higher throughputs.

EXAMPLE V In another series 'of runs carried out in the same apparatusas employed in Example I, an inert gas was introduced to the face ofelectrode 46 via conduit 50. in this series of runs no ionizationinitiator was used. Prior to initiating the discharge, a mixture ofpropane and air at a stoichiometric level of about 108 per cent wasburned in tangential inlet tunnel 28 for a period of time sufficient forthe refractories to reach a temperature above about 2,200 F. Thedischarge was initiated by simply turning on the power and a distributeddischarge was obtained immediately due to the hot refractories. Afterequilibrium had been established (Run l-control), a stream of nitrogenwas introduced through conduit 50 for Run 2. Data for the two runs areset forth in table V below.

Comparing Run 1 with Run 2 shows that the power level (kw.) in Run 2 wassome greater than in Run 1. However, it should be particularly notedthat the discharge voltage in Run 2 was considerably greater than inRun 1. While it is not intended to limit the invention by any theoriesas to operation thereof, it appears that the inert gas introduced viaconduit 50 produces a cool region around the face of electrode 46, thuscreating a region of higher resistance due to decreased ionization. Thisapparently results in an'increase in the discharge voltage and puts moreenergy into the distributed discharge at about the same current level.

For the purposes of this invention, nitrogen is considered as an inertgas. Any suitable inert gas such assaid nitrogen, helium, argon,crypton, xenon, and neon can be employed in the said inert gas soemployed can be any suitable amount sufficient to cause an increase inthe discharge voltage but insuffi-- cient to disrupt the discharge. Aswill be understood by those skilled in the art in view of thisdisclosure, the discharge can EXAMPLE Vl A run was made in a furnaceessentially the same as that iilustrated in FIGS. 1 and 2 except thatsaid furnace was provided with only one tangential inlet tunnel 28. Thediameter of the face of electrode 46 was about seven-eighths inch, andthe spacing between electrodes 46 and 16 was about 2.5 inches. in thisrun a fuel-rich combustible mixture of air and propane was burned insaid tangential tunnel and the resulting combustion gases passedtangentially into chamber 26. A distributed discharge was establishedbetween said electrodes and across and/or through said combustion gasesby first using a stoichiometric mixture of air and propane to obtain atemperature of about 3,300 F., which served to ionize the gases andestablish a distributed discharge. Thereafter the flow rates wereadjusted to those given intable Vl below. The make hydrocarbon wasethylene and 17.1 s.c.f.h. was introduced via conduit 50 axially intochamber 26, passed therethrough, and then passed into chamber 12 whilesurrounded by the electrically augmented hot combustion gases. Theefiluent gases from chamber 12 containing the carbon black' productsuspended therein were quenched in conventional manner and said carbonblack separated therefrom in conventional manner. Tests on the carbonblack product and operating conditions for said furnace are set forth intable Vl below as Run No. 1.

EXAMPLE Vll Another run was carried out in the same furnace employed inexample VI. In this run a mixture of air and propane was used as thesource of combustion gases and also as the source of the makehydrocarbon or reactant. This run was initiated by passing 520 s.c.f.h.of air at 130 percent of stoichiometric with propane through thetangential inlet 28 to establish a swirling turbulent mass of gases inchamber 26. A distributed discharge was established across said mass ofgases by first applying a high initial voltage of about 6,000 volts andthen reducing the voltage to the operating voltage of 1,690 volts. Aftersaid discharge had been established the airflow was reduced to 145s.c.f.h., thus reducing the stoichiometric level to about 31 percent.Said electrical discharge heated the mass 'of gases to carbonblack-producing temperatures and carbon black was formed from a portionof the propane contained in the mixture of gases. The carbon blackproduct was separated from the effluent from chamber 12 in conventionalmanner. Operating conditions on the furnace and tests on said carbon bedisrupted by injecting too much inert gas thus cooling black product areset forth in table Vl below as Run No. 2.

' TABLE VI Furnace Conditions Carbon Black Product Electrical PowerInducefrae- Oil ab- Ngsuriace Air Propane Stoiehio B.t. tiveIm- Percenttory sorption', area, sq.

rate rate, metric, per pedenee, Power Percent of com- Temp., ccJgrammeters] Run s.c.f.h. s.c.i.h. percent hr. ohms Volts Amps Kw. factor oftotal bustion F gram EXAMPLE VIII The carbon black obtained in exampleVI was compared with a carbon black of commerce having about the samesurface area in the compounding of a SBR rubber; the results show that ahigh-quality black was produced by electrical augmentation of thehydrocarbon flame:

Santocure (c) L3 Physical Properties of Vulcanizates Black Used ExampleVl Philblaclt B (d) MXIO, moles/cc (c) [.64 [.6] 300% Modulus, p.s.i.(f) 980 I370 Tensile, p.s.i. (f) 3520 3660 Elongation, I: (I) 690 570(a) An emulsion polymerized butadiene-styrene rubber made by the recipein ASTM D l4l9-6l.

(blAphysical ofa as,- t. r and '-diphenyl-p-phenylene-diamine (35%) (c)N-cyclohexyl-2-benzothioazole sulfenamide.

(d)'A super abrasion furnace black having a surface area of about 135sq. m.g.

(e) Rubber World 135, 67-73, 254-260(1956).

(f) ASTM D 4l262T. lnstron Tensile Machine. Tests were made at atemperature of 80 F.

The above examples show that the method and apparatus of the inventionare valuable tools for the production of hightcmperature gases andproduction of carbon black. As shown by the examples, the apparatus iscapable of operation over a wide range of operating conditions, withfew, if any, real limitations except those imposed by size or capacity.For example, no maximum in power level was found within the maximumlimits of the electric circuit employed. The burner or furnace of theinvention can be operated over a wide range of stoichiometric ratio ofair to fuel, e.g.,' at least from about 30 to aboutl60. From 25 to 90percent of the heat required in producing carbon black can be suppliedelectrically.

The burner or furnace of the invention has a number of advantages. Animportant advantage is that heat losses are minimal. An outstandingfeature is the electrode system. No cooling is required on thedownstream electrode. In operation, the distributed discharge at theelongated downstream electrode is spread over a substantial portion ofthe electrode length, frequently the entire length. This spread wouldnot take place if the electrode did not have an elongated tubularconfiguration. Said elongated configuration has the further advantagesof making possible a short electrode spacing for discharge initiationand a long spacing for high discharge voltage and high power input.

As used herein and in the claims, unless otherwise specified, the termfree oxygen-containing gas includes air, air enriched with oxygen, andessentially pure oxygen.

The term stoichiometric level, as used herein and in the claims, unlessotherwise specified, refers to or is measured with respect to the oxygencontent of the free oxygen-containing gas and is considered on the basisof complete combustion to carbon dioxide and water.

While the invention has been described as using a vaporous hydrocarbonas the feedstock for the production of carbon black, the invention isnot so limited. Carbon black can be produced in the burner or furnace ofthe invention from any of the known gaseous or liquid essentiallyhydrocarbon feedstocks normally used in the carbon black industry.

The high-temperature gases produced in the practice of the inventionhave uses other than in making carbon black. Said gases can be used inmetallurgical processes such as the thermal reduction of metal ores.Said gases can also be used in chemical processes requiring hightemperatures. In those embodiments of the invention wherein carbon blackis a primary product, the gases remaining after separation of the carbonblack therefrom, while not having as high a temperature as when carbonblack is not being produced, are still valuable for heat exchangepurposes. For example, said remaining gases can be used for theproduction of steam by heat exchange in a suitable heat exchanger orboiler.

While certain embodiment of the invention have been described forillustrative purposes, the invention obviously is not limited thereto.Various other modifications will be apparent to those skilled in the artin view of this disclosure. Such modifications are within the spirit andscope of the invention.

What is claimed is:

l. A process for producing high-temperature gases which comprisesestablishing an electrical discharge in substantially uniformdistribution throughout a zone, passing a gas throu b said zone in theabsence 0 a flame In said and m contact WI b said discharge to increasethe temperature of said gas, said electrical discharge being distributedsubstantially uniformly through said gas upon passage of said gasthrough said zone.

2. The process as described in claim 1 in which an ionization additiveis present in said gas.

3; The process as described in claim 1 in which said electricaldischarge is established between two spaced electrodes one of saidelectrodes being subjected to a current of between about 0.08 amperesand 0. 12 amperes per square inch. 7

4. The process as defined in claim 3 in which the electrode voltage isbetween about 285 and about 465.

5. The process as defined in claim 4 in which the discharge voltage isfrom about 975 to about 2,080.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dat January 18,1972 Patent Noe 3,636,300

'l'homas J. Gunnell and Albert F. Stegelman It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 1h, line 43, claim 1, after said, second occurrence, I insertzone Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M.FLJ:;TCHER,JR. ROBERT GOTTSCHALK Commissioner of PatentsAttesting Officer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQNDated: January 18, 1972 Patent No, 3,636,300

Thomas J. Gunnell and Albert F. Steggelman It is certified that errorappears in the above-identified patent and that said letters Patent arehereby corrected as shown below:

Column 1 line +3, claim 1, after said, second occurrence, insert zoneSigned and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GQTTSCHALK Commissioner of PatentsAttesting Officer

2. The process as described in claim 1 in which an ionization additiveis present in said gas.
 3. The process as described in claim 1 in whichsaid electrical discharge is established between two spaced electrodesone of said electrodes being subjected to a current of between about0.08 amperes and 0.12 amperes per square inch.
 4. The process as definedin claim 3 in which the electrode voltage is between about 285 and about465.
 5. The process as defined in claim 4 in which the discharge voltageis from about 975 to about 2,080.